Composite material and process of making the same



Patented Aug. 30, 1932 PATENT OFFICE EMIL C. LOETSCHEB, F DUBUQUE, IOWA.

Np Drawing. Application filed Apr-i117,

hardness, smoothness and finish obtainable in hardwoods only bypainstaking and tedious hand labor.

Inasmuch as the process is applicable. for the. production of variousarticles in which fibrous or cellulosematerials are substituted fornatural woods, the following description will be confined to the methodof making a door panel as illustrative of the general procedurefollowed.

The base material for the panel or other piece to be made, may be anyone'of a number of prepared fibre or pulp boards used for insulationand'wall construction, and consisting of a mass offibres compressed intoa solid sheet and having the characteristic fibrous surface texture.Having prepared a piece of the base material of proper size andthickness for a panel, the first step in its treatment s to spray on orotherwise apply to the surface. a solution of a phenol-condensationproduct. such as Bakelite and alcohol, although certain natural gums maybe used in place of Bakelite. such as shellac, kauri or Congo gum.Bakelite is preferred as it produces a superior finish but is morecostly, and therefore a cheaper substitute will often suffice, or insome cases. the Bakelite is replaced in part by one of the cheapernatural gums,- the proportion of Bakelite, however, deter- .mining thequality of the ultimate surface finish.

After the treament with the Bakelite solution and while the surfaces tobe finished are still partially wet and in tacky condition, a coating ofpulverized or finely dividedfibrous or cellulose substance. such as woodflour or ground eornstalk pulp, is sifted over the surfaces to form acoating of substantial thickness. This dry coating is then pressed intothe varnish-like surface by means of roll- COMPOSITE MATERIAL ANDPROCESS OF MAKING THE SAME 1929. Serial No. 355,992.

ers passed over the surface, or by passing the coated panel betweenpower driven rollers, whereupon it is then subjected to a drying processin a suitable dry room or enclosure whereby the solvent remaining in theBakelite solution is driven off, leaving the'surface coating practicallydry.

As a practical and satisfactory variation in the process, any suitablefibrous material 1n sheet or woven form, such as heavy paper, cardboard,or cloth, may be used in place of the pulverized substancesbefore-mentioned. In this case, I prefer to use a thin solution of Congogum spirit varnish dis solved in a suitable solvent, with or without theaddition of varying percentages of Bakelite varnish as the primarycoating for the panel surfaces. I find that Congo gum is Verysatisfactory as an adhesive. in addition to having a high melting point,and combines readily with Bakelite, the latter being advantageous due toits hardening qualities.

In some respects the use of paper and the like is advantageous, in thatit provides a veneer over the base material and as such materiallyincreases the strength.

Continuing with the next step in the process. the dried panel is nowsubjected to a combined heat and pressure treatment, a press of thehydraulic type. being preferably used for this purpose. Moreover,especially prepared platens or plates are provided, the same beinghollow and provided with corn nections for the circulation of steam andcooling water theretlnmigh for heating and cooling the platens.Depending on the degree of compactness desired in the finished panel,the pressure exerted may varyfrom 100 to 1000 pounds per square inch. itbeing evident that the greater the pressure the greater will be thestrength of the panel. The pre sure is applied for a period of from fiveto ten minutes, during which time the platens are heated, whereupon theyare allowed to cool, down to the normal temperature or be artificiallycooled in the manner already suggested. 5y reason of the application ofheat. the resinous substance or Bakelite, or a mixture of the two as thecase may be, become hardened or set, and with the accompanying pressureand cooling, a hard and smooth surface finish is produced, showing noneof the characteristic fibrous texture of the raw base material.

Upon removing the panel from the press, it is ready for the finalsurface finish. I or ordinary surface decrn'ation, paint, enamel,

lacquer orvarnish may be applied to the panel in the same manner as theywould'be applied to a wood panel, although fewer coats are required dueto the smooth and uniform character of the surface. If desired. thesurface may be grained in imitation of natural wood by any suitablegraining or grain reproducing process, and a final protective coat ofvarnish applied. or if a more finished surface is desired. severalcoatsofnatural resin varnish or lacquer may be applied in the usual mannerand rubbed down, as in the case of natural wood finishes.

v However. to produce what may be regarded as a fine finish, the paneln'iaytbe. further theated as follmvs:.-\ssuming that the panel has beenremoved from the press after the combined heat and pressure treatment. a

fairly heavy solution of Bakelite varnish is applied overthesurface, andthe panel again placed in the drying room for the purpose of expellingthe solvent in the Bakelite varnish solution. At first, the drying isallowed to continue slowly at a relatively low temperature, whichisgraduallv increased to from 240 to280 R, at which temperatures the Inthis manner, the Bakelite coating is subjected to a temperature of say250 F. to

, 275 F. for a period sufficient to cure the Bakelite. Ordinarily,one-half hour atthe temperature stated is adequate, although the naryacids and solvents, or exposure to temperatures as high as 400 F. a I

As will be seen from the foregoing, the process may be carried only tothe pointof producing finishes suitable for ordinary interior work, ormay continue to the point of providing an exceedingly: hard and lastingsurface. having all of. the lustre and beauty obtainable in naturalwoods, but of greater desirability and at a greatly reduced cost, bothas to the raw materials and the labor involved.

Havingsct forth a preferred embodiment of my invention, I claim as newand novel:

1. A process for producing-a composite material consisting of coating asheet of base material composed of a partially compressed 1 mass ofcellulosic fiber pulp with a resinous varnish and. drying the same toprovide ..a tacky surface, applyinga thin layer of pulverized fibrousmaterial over'said surface, subjecting said basesheet to heat andpressure,

applying a solution of a phenol-condensate product over'the surface ofthe treated sheet and again subjecting the same to heat sufiipient torender said product hard and infusible.

2. A process for producing a co mp osite.

material consisting of coating a sheet, of fibrous material derived fromcorn-stalk or wood pulp with a resinous varnish, applying a thin layerof fibrous material over said f coated surface. sub ectmg said basesheet to p, 1

heat and pressure treatment, applying a phenol-condensate product overthe surface of the treated sheet and again subjecting the same to heatsufficient to rendersaid product hard and infu sible.

EMIL. C. LO ETSCHER.

time may be shortened by increasing the temperature.

During the heating processin the press, the Bakelite first becomesfusible and spreads over the surface of the panel in a smooth, evenfilm, and later becomes infusible. WVhen this condition is reached. theplatens are then cooled by water, and the panel removedfrom the press.

This final-treatment with Bakelite varnish produces an exceptionallyhigh grade finish and one capable of withstanding hard wear and usage,and injury by contact with ordi- Signed at Dubuque this 12 day ofAprihg. I

